As discussed in the parent application, many work sites, such as construction sites, mining sites, farming, logging, gas and oil drilling sites, as well as others, often occur in areas where there is no prepared road bed. It is customary in the oilfield industry to have the requirement of transporting heavy machinery on trucks to remote areas in fields and the like where there is no prepared roadbed. Such areas may be on soft ground, mud, swam, wetlands, tundra, muskeg, sand, or the like. Often these roads are located in areas that are subject to extreme temperature ranges and must be left unattended for great lengths of time. Accordingly, these roads are subject to extreme conditions.
The axle loading of a typical heavy equipment truck is such that it is not feasible to drive it across a scraped or unprepared ground surface without experiencing sinking, jamming of the truck, and similar impediments. Accordingly, heavy equipment used at the work site requires a suitable road bed that is stable to prevent the equipment from becoming stuck in the soft ground. These vehicle also require a road that is fairly smooth. However, the nature of the industries causes the roads to traverse extremely rugged and uneven terrain. Accordingly, there are at least two competing interests in these roads: requirements for a stable and smooth surface, which must be considered against the constraints associated with uneven and unstable terrain. Exacerbating the problem is the fact that many of the roads, once constructed, will remain unattended and unrepaired for great lengths of time. Heretofore known roads have been deficient in balancing these competing objectives and the constraints placed on the roads.
Furthermore, there are frequently regulations associated with performing work in environmentally sensitive areas, which require the site to be returned to its original pristine condition when work is completed. Such site restoration can become quite expensive and labor intensive. Accordingly, while the art has been concerned with ground surfaces incapable of supporting the weight of a motor vehicle, there is now a further need to protect environmentally sensitive areas in order to reduce environmental damage.
A common practice for many years has been to construct a temporary road bed from wood planks that are laid on the ground and nailed together. Typically, a second and third layer of wood planks are laid on top of the base layer in alternating directions and secured together by nails. The number of layers of wood planks can vary depending on the stability of the ground and the weight of the equipment that will travel over the road as well as the environmental conditions surrounding the road. Various methods have been proposed to form a temporary road bed using preassembled mats constructed from wood boards. These mats typically include a structure for interlocking with an adjacent mat. These preconstructed mats are generally intended to be reusable by disassembling the road bed and transporting the mats to a new location.
Construction of a temporary road bed using individual boards is costly and labor intensive. The heavy equipment that travels over the road bed often damages a large number of the boards so that the boards cannot be reused. Disassembly of the road bed is also labor intensive and damages many of the boards not previously damaged during use. As a result, a significant portion of the boards used to construct the road bed are discarded. Still further, roads formed of wood are subject to degrading, separation and the like. If nails are used to connect boards, these nails can become dislodged and may damage the tires of vehicles traversing the road. If the nails become dislodged, the boards can become separated which can damage the tires of vehicles traversing the road or even producing slick spots. Still further, if the wood becomes damaged or nails fall out, elements of the road may remain after the road is removed thereby causing undesirable environmental damage. If the boards become separated, vehicles may cause damage to the ground in the open areas, again causing undesired environmental damage.
Therefore, temporary roadways formed entirely of wood planks as taught in the prior art have many undesirable characteristics.
Numerous examples of preconstructed mats for use in constructing a temporary road bed or flooring system are known. However, the prior methods of constructing a temporary road bed are generally expensive and time consuming. Although the preconstructed mats can reduce the time for constructing a temporary road, the cost of manufacturing the mats and the difficulty of moving and assembling the mats have limited their use.
In view of the deficiencies of the prior methods and devices, a continuing need exists in the industry for an improved method and device for constructing a temporary road bed.
This need has been approached by several methods. For example, the inventor is aware of several methods and devices for forming a temporary road bed from elements other than wood, such as rubber from discarded tires. However, the heretofore proposed methods of forming construction mats from discarded tires required the components parts of the individual tires to be separated from the tire, that is, the separation of the tire tread section from the tire sidewall section. These methods also required the individual tire segments so separated to be fixed or arrayed in a uniform or consistent manner before being linked together to form a mat. These steps in the prior methods are expensive and time consuming. Other known methods are also time consuming and labor intensive.
Still further, these known methods do not produce a mat that is stable and which has a good memory so it will return to its initial condition after supporting a very heavy load, even a load as high as thousands of tons which is common in the construction and oil drilling industry and even if the road is located in an area that is subject to extreme environmental conditions and which may be left unattended for great lengths of time. Heretofore known mats are quite likely to become damaged and permanently distorted by such heavy loads and conditions. A damaged or distorted mat must be replaced, which can add expense to the overall job through the cost of materials as well as the cost of labor, which is doubled because the damaged or distorted mat must be removed and then replaced. An unreplaced damaged road may create a hazard to vehicles and to the environment.
Consequently, a need exists for improved pavement mat as well as for improved methods in making the mat that will allow the formation of mats from discarded tires in less expensive and time consuming manner and that allows for the use of discarded tires as a mat component without requiring the separation of the component parts of the tire during the mat assembly process.
There is a further need for an improved mat which will be very stable and not likely to become permanently distorted by a heavy load, and will not tend to deteriorate or dissociate under such heavy loads and under harsh environmental and terrain situations even if left unattended for extremely long periods of time.
The temporary roadway element disclosed in the parent application overcame the above-mentioned problems and proved to be very successful in achieving the above-discussed objectives and ends. However, even with such an improvement, there is a continuing need to still further improve temporary roadway elements such as the one disclosed in the parent application.
The inventor is also aware of a rubber access mat disclosed in Canadian Patent 2,473,000 which is a rubber slab having a grid of steel wires embedded therein. The grid of steel wires includes wires extending longitudinally of the mat and wires extending transversely of the mat to define an orthogonal pattern in the rubber. This access mat is disclosed as being useful for forming a roadway or pathway for vehicles and people. While working in some conditions, the mat disclosed in this Canadian Patent has several drawbacks, for example, inter alia: the wire grid inside the rubber tends to cut the rubber when heavy loads are applied; the thermal properties of the steel wires are disadvantageous, especially in the extreme conditions in which the mats are to be used; the steel wires tend to move with respect to each other and with respect to the mat thereby creating delamination problems and defining voids within the rubber; the steel wires are often flexible and do not have a good shape memory so that once flexed, the mat may not return to its original shape which had been designed for maximum effectiveness thereby creating problems for the overall mat with regard to the terrain and with regard to load support features as well as exacerbating the just-mentioned problems; the steel of the grid does not have thermal properties that are advantageous to the rubber mat; and the orthogonal arrangement of the steel wires in the mat disclosed in the Canadian patent is not the most efficient arrangement for supporting heavy loads under the environmental conditions in which the mat is used. Furthermore, the preferred form of the mat disclosed in the Canadian patent includes two layers of grids which may tend to exacerbate the problems associated with delamination and void formation, the problems associated with rubber cutting, and problems associated with varying thermal properties. As an example of the problems associated with the mat disclosed in the Canadian patent, it is observed that movement of the steel wires in the mat may create voids in the mat which, themselves, will create problems. For example, if the wires move either due to the application of a load to the mat or due to thermal conditions or due to uneven terrain, they will tend to cut the mat and form voids which will weaken the mat and may make the mat susceptible to moisture invasion into the mat which will weaken the mat and may increase the size of the voids upon freezing. A weakened mat may tend to damage the terrain under heavy loading. Furthermore, a weakened mat may tend to break thereby vitiating the purpose of the mat.